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AR, what you are saying is a dharmic way, it's like asking why take action in maldives let them sort out things. Unfortunately, I do not see geo politics going dharmic anytime soon. S. Radhakrishnan kept on harping about Nuremburg trials and right determining the might of nation v/s might determining the right. Sometimes "dhamakas are necessary to make others know you are there", after 10 years of UPA we need some dhamakas to show dont take us for granted

Panditji, these are unrelated topics so would not comment on Maldives issue here. Nevertheless, what I was coming to point was shock factor is the most potent weapon in numbing the opponent. This is what happened to Alexander when he was presented with numbers of elephants that they may face in next battle in India; bit like upper cut in boxing. I for once has least interest in classification and range and type of weapon system presented in the brochure. All I care is whether I can land one of them where I intend to on the day or not. Example: Having one khatun like Aishwarya is better than having 4 Sneha ullal's around..Missiles are only effective against countries with weak anti missile defence. Once you have build a layers of BMD, it can be easily be intercepted like we see in those being intercepted in Saudi Arabia fired from Yemen.

Indranil ji, Was away for last many days, so let me respond to evolve teh discussion

Indranil wrote:

Haridas wrote:Sorry sir I will have to take you to the mat.

With due respect sir, I don't mind being taken to the mat with proper logic and reasoning. But what you say makes no sense to me at the moment.

Haridas wrote:Really ? Wrong !

Isn't the typo obvious there. I meant Agni III.

I only rebutted what you wrote. If you say it was a typo error, so be it, no issue.

Indranil wrote:Agni VI has the same three stages as Agni V, except its first stage has a composite case. The throw weight increases from 1 ton to 3 ton.

Indranil wrote:

Haridas wrote: wow the composite stage casing must be generating thust (using unobtainium), or is a wishful thinking with no scientific fesibility/foundation.

If you make the upper stage lighter, it has a remarkable effect on the size of the booster required.

Sure, the issue at hand is to quantify "remarkable effect" due to change of casing from maraging to composite. What in your understanding would be typical/reasonable mass fraction difference for a booster sized stage when made of maraging steel versus composite? That will allow one to estimate the quantitative effect.

Indranil wrote:While I am not completely right in making the bolded statements above (more on that later), the following are slides from Dr. Saraswat.The payload increases from 1 ton to 3 ton with only a marginal increase in weight. Notice that he highlights that all three stages are made out of composites. Agni VI will actually have a new first stage which weighs 40 tons. The diameter will be slightly larger (presumably 2.3 mtrs) than that of the A5. While revealing this in 2013, Dr. Chander also said it is a technological challenge that the country has to overcome, i.e. to build a composite booster.

Please show me in the slide or any DRDO publication where it says the difference between the two rockets is mainly (or solely) booster stage being composite vs maraging? Wrong or incomplete reference to substantiate your assertion. Staging on its own is a well known method to increase the propulsive efficiency of rocket; 2 stage to 3 stage in this case.

Indranil wrote:

Haridas wrote: She is a scientist & engineer and would speak in measured way within a context, but surely who listened and reported it must be a dumb dork media reporter, for it is impossible to transform 48 tonne solid fuel missile throw capabelity (even assuming maraging case) into a 22 tonne solid fuelled craft no matter the level of optimization. I would be happy to be proven wrong (and eat vegitarian crow equivalent) if someone can kindly show scintifically / mathamatically it's viability using earthly material, much less material and techniques that isro or drdo has demonstrated.

It was not one reporter who reported, but a few.

She said they completely redesigned Agni III, just like they are doing for Agni 1 now. In the new Agni 3, the upper stage has a composite casing. It has new lighter avionics and has single digit accuracy. Hence, they decreased the payload from 2.5 tons to 1.5 tons. Even Avinash Chander spoke of the reduction of the payload. Now, if they dropped 2 tons or so from the second stage and made it much more efficient, how big does the booster need to be. Another way to ask the question is if it takes 16 tonnes for Agni IV to lob 1 ton to 4000 kms, how many tons does it need to lob 1.5 tons to similar distance. Suddenly, the 22 tons seems plausible, doesn't it?

Composite stage optimization alone can't reduce weight from 48 tonne to 22 ton. If Agni-III is in the first place un-optimized & loaded with tons of other deadweight (specially in upper stages) then definitely eliminating that dead weight will drastically reduce rocket size & weight; much more drastic compared to dead-weight reduction of rocket casing mass when switching from margaing to composite.

Indranil wrote:On the other hand, you are asking me to believe that the guys always had the technology to build the motor casing of the booster using composites, but not the upper stages. So, in Agni III, they used composites for the lower stage and maraging steel for the upper stages. And then they went to Agni V wherein they discarded the composite casing from Agni III and started using a steel casing again. How does this stand your sanity test?

...wonderful book by Gopal Raj’s Reach for the Stars: The Evolution of India’s Rocket Programme. Raj details how India licensed the solid propellant technology for the Centaure II sounding rocket from France’s Sud Aviation that started them on the road to not only their space launch capabilities (such as the SLV-3) but also to the Agni guided missile.

The Centaure II uses relatively modest propellants (Polyvinyl Chloride—PVC—binder and ammonium perchlorate—AP—oxidizer) but licensing this technology enabled India to gain invaluable experience producing large-grain solid-propellant rockets. India was able to produce part of these chemicals by purchasing a PVC turnkey production plant from B.F. Goodrich but they first had to import AP. Interestingly, India was able to capitalize its preexisting electrolytic industry in the form of the West Indian Match Company (WIMCO) to jump from potassium perchlorate to ammonium perchlorate, which required an additional electrolysis stage. WIMCO was created as a joint venture where India licensed the technology from the Swedish Match Company in 1924 as a turnkey plant, Indian engineers had assimilated the technology by the 1960s so that they were able to modify it enough to produced ammonium perchlorate

That was our approach to the repackaging of our vehicle. We made major modifications in the upper stage. V.G. Sekaran, Director, Advanced Systems Laboratory [ASL], DRDO, played a primary role in showing us how to repackage the payload structures so that the weight comes down by 1,000 kg.

Most crirical to undetstand the net improvement in throw-weight or range. That 1000 kg on payload structure corresponds one to one to payload rating improvement.

If the payload repackaging came down by 100o Kg then would it be possible using the weight to range curve be calculated ?I think the curves for Agni 1 and 2 were done isnt it.Also could the percentage of net weight reconfiguration in the multistage rocket equation be done to calculate the new total weight working backwards ?

^^^ Yes, if one has estimate of the fuel fraction for the stages (which is based on technology & engineering capability), then for a given throw weight & range one can back calculate the expected launch weight for a "N" stage rocket.

Agni V is not just more accurate, but is also more reliable and indeed survivable. While its 2.0-m-diameter first stage motor is the same as that of the Agni III (which incidentally has gone into production recently) and made of 250 grade maraging steel, its second and third stages have carbon composite casings. ...

In the future, even the first stage of the Agni V may use carbon composite motor casings and that would take care of the issue of corrosion altogether and enhance overall structural integrity.

Beyond composites, DRDO has also developed a new grade of low alloy steel designated DMR 1700 which can effectively substitute 250 grade maraging steel in missile applications, ranging from the skeleton to the 2.0 m diameter motor casing used in the first stage of the Agni V. DMR 1700 is significantly cheaper than maraging steel and may ensure that the production of strategic missiles advances quickly. So, although, we have waxed eloquent on composite motors, thus far an alternative for even more cost effective and quicker production probably exists.

Second and third stage motors made of advanced, high performance, lightweight fibre reinforced composite materials resulting in very significant weight savings, thus extending the range of the missile....What makes Agni-5 different from earlier ones in series, ... For instance, extensive use of light weight ‘Advanced Structural Composite Materials’ and superior composite solid rocket propellant helps it achieve higher payload capability range without much increase in weight as compared to its predecessors.

It does not make sense: composite casing for the booster and steel casing for the upper stage for Agni V or Agni III or any rocket for that matter. If you have the capability to build the former, you would have the technology to build the latter (which is 1/3 in size and also requires lower strength). Also, if Agni III used a composite booster casing, so would Agni V.

If you are convinced that the original Agni III used maraging steel for both the upper and lower stages, then we can move on to the next problem: what would an optimized Agni 3 look like, and why would it weigh more than twice that of K4? Both have the same payload and range characteristics and designed and built by the same organizations.

Myth 1: Agni III has composite casing for the booster, but maraging steel casing for the second stage.

Indranil ji, Pls see my earlier response. It is not a point of contention, as I said earlier it "my chaiwalla's saala" chatter in very early days of first test launch that failed. But good reverse psyop op those days on non proliferation ayothullas; all the time doubting on similar lines as you. So let us move on.

But the references you mention has interesting segways. Last i looked into it some 12 yrs ago, I did not see very significant mass fraction difference between Maraging steel and equivalent strength composite material. Maraging was easier to handle compared to composite. Now Jha says DR 1700 also competing for the job. I am too lethargic these days, if some metellurgy guru can share insight on it.

Second and third stage motors made of advanced, high performance, lightweight fibre reinforced composite materials resulting in very significant weight savings, thus extending the range of the missile....What makes Agni-5 different from earlier ones in series, ... For instance, extensive use of light weight ‘Advanced Structural Composite Materials’ and superior composite solid rocket propellant helps it achieve higher payload capability range without much increase in weight as compared to its predecessors.

The devil is in the details, in quantifying the value of the ISP of the "superior solid rocket propellent" ! (Do you/anyone know the isp? Contrast it with isp of PSLV s PS3 which is amongst the highest solid fuel isp that isro has developed. Space application being civilian field, it is less challenging, thus yields higher performance). All solid rocket fuels have a relatively low and narrow range of ISP , that is way below earth storable liquid fuel isp [As an aside DRDO tech pub published a nice book on solid rocket propellant many years ago]. OTOH CL20 derived very expensive solid fuel is thus used spareingly for small mil rockets like sam, iirc.

Looking at the mijjile.1. I see what appears as control rods (actuator on right side) to drive the c0ntrol fins. Appears aerodynamically unprotected suggesting it will receive a shroud.2. Near stage coupling, looks like jet exhaust ports. For post launch reorientation?3. The main stage can be seen in background above the heads.

Haridas wrote:Looking at the mijjile.1. I see what appears as control rods (actuator on right side) to drive the c0ntrol fins. Appears aerodynamically unprotected suggesting it will receive a shroud.

Yes they are indeed control rods. On the actual missile they are protected under a fairing. It will be interesting to see if they retain this in the Akash NG. NG will be canisterized, so may be they will move to smaller folding all-moving wings. Also now they have now developed various compact rotary fin actuation systems. So it will be interesting to see if they retain this method of actuation using push-pull control rods.

Haridas wrote:3. The main stage can be seen in background above the heads.

Could not follow this part. Akash uses an integral ramjet. After the solid-fueled booster grains have burnt out, the cavity left behind forms the combustion chamber for the ramjet engine. In front of the "joint" is the sustainer fuel, control system, warhead and guidance mechanism.

For an SR SAM it is mightily large! Look at the current crop of SR SAM's, far smaller.However, I always thought that Akash was intended to be a med.range SAM, replacement for our legacy Sov. era SAMs.Now canisterised, perhaps my long standing query about a naval variant might happen.

The IN despite BMos, Klub, etc., is looking for around 300+ new med. range SSMs ( around 300 km range) and has thrown open the door wide.Surely we could've developed our own Desi SSM after so much of experience from naval Dhanush/ Prithvi, BMos, Nirbhay, etc.? Plus acquisition of Exocet and Harpoon as well.These SSMs may be destined to replace Sov. era SS-N- 2D Styx and some Uran's too.

Yes it is large. But it is not inefficient . It is powered all throughout unlike solid rocket based missiles which coast for very long periods of flights. You don't want to be painted by this thing. It is going to chase you hungry hound. with nose based terminal guidance and and state-of-the-art ground based radar, the NG is one of the most potent land based SAMs where size and weight don't matter.

In the same vein. I don't think it is going on our ships because of its size and weight. QRSAM+LRSAM is the best bet there.

Indranil wrote:Yes it is large. But it is not inefficient . It is powered all throughout unlike solid rocket based missiles which coast for very long periods of flights. You don't want to be painted by this thing. It is going to chase you hungry hound. with nose based terminal guidance and and state-of-the-art ground based radar, the NG is one of the most potent land based SAMs where size and weight don't matter.

In the same vein. I don't think it is going on our ships because of its size and weight. QRSAM+LRSAM is the best bet there.

Plus all the other small form factor sams don't have the ceiling this one has.

1. I agree with you that the Isps of the upper stage of Agni III/V is unlikely to be better than the upper stages used by ISRO. But I don't think that DRDO is using kevlar for the upper stage. I think they are using some glass composite which does not have the same strength but is much lighter. I forgot where I read it. It was a book written by two ISRO scientist. They had studied glass composites which where 67% lighter than Kevlar (obviously with commiserate loss of strength).

2. I have never seen any pictures of the modified Agni 3. For example, here's the website of the company that makes the TELs for Agni and other missiles: Gallery defence and Products Defence. Note the only trailer missing: Agni 3. I lost an important document: ANS had floated a tender for the transporter of K4. I don't think I can trace it again. It had the details of weights/diameter and length of each stage. That was revealing. AFAIK, the total weigth was indeed in that 20-25 Ton range. Note that Deftec also has a 25 ton trailer for which it did not produce any pictures.

3. One hint that Avinash Chander dropped was that weight savings from the composite upper casing, lighter payload and systems etc. is equivalent to the weight of the third stage. We can start from there. What is the propellant mass required for the second stage of Agni 2 if the payload + inert weight is dropped by the weight of the third stage of Agni V. We can ignore the higher Isp and more efficient stage separation for now.

Haridas wrote:Looking at the mijjile.1. I see what appears as control rods (actuator on right side) to drive the c0ntrol fins. Appears aerodynamically unprotected suggesting it will receive a shroud.

Yes they are indeed control rods. On the actual missile they are protected under a fairing. It will be interesting to see if they retain this in the Akash NG. NG will be canisterized, so may be they will move to smaller folding all-moving wings. Also now they have now developed various compact rotary fin actuation systems. So it will be interesting to see if they retain this method of actuation using push-pull control rods.

OK it is indeed Akash, I was thinking it is some other missile. I had taken so many close up pics of Akash many many yrs ago, and now didn't recognise what it looked under its clothings !

well those things are ram air plumbing in to the chamber, at 90 degrees x4, intake nested between front fins.

Indranil wrote:

Haridas wrote:3. The main stage can be seen in background above the heads.

Could not follow this part. Akash uses an integral ramjet. After the solid-fueled booster grains have burnt out, the cavity left behind forms the combustion chamber for the ramjet engine. In front of the "joint" is the sustainer fuel, control system, warhead and guidance mechanism.

Yaakwaala can confirm but I believe that section has the solid fuel for ram jet. I am told a marvellous design, where controlled amount of partially oxidixed fuel is burnt and fed into jet engine chamber.

1. I agree with you that the Isps of the upper stage of Agni III/V is unlikely to be better than the upper stages used by ISRO. But I don't think that DRDO is using kevlar for the upper stage. I think they are using some glass composite which does not have the same strength but is much lighter. I forgot where I read it. It was a book written by two ISRO scientist. They had studied glass composites which where 67% lighter than Kevlar (obviously with commiserate loss of strength).

Indranil ji, you think the DRDO scientists assertions were credible? To lay reader it will sound like walking on water, but in reality misleading.

OTOH IIRC in my post i didnt claim or asserted the use of kevlar. So i will like to know more about agni composite stages.

2. I have never seen any pictures of the modified Agni 3. For example, here's the website of the company that makes the TELs for Agni and other missiles: Gallery defence and Products Defence. Note the only trailer missing: Agni 3. I lost an important document: ANS had floated a tender for the transporter of K4. I don't think I can trace it again. It had the details of weights/diameter and length of each stage. That was revealing. AFAIK, the total weigth was indeed in that 20-25 Ton range. Note that Deftec also has a 25 ton trailer for which it did not produce any pictures.

A) I too recall that tender. But the size and wt, is so different from A3 that it would be unwise/unreasonable to call it a modified A3.B ) Your assertion of 'composite case booster resulting in payload increase from 1 ton to 3 ton' can't be justified on the basis of expected mass fraction improvent and mirginal ISP increase.

3. One hint that Avinash Chander dropped was that weight savings from the composite upper casing, lighter payload and systems etc. is equivalent to the weight of the third stage.

But iirc your argument was the throw weight (payload) increased for the given datum range.

Nevertheless adding an additional stage is a major reconfiguration of the rocket, not a progressive evolution of a baseline where efficacy of a design change can be evaluted on resulting system performance measure (as a partial differential coefficient).

We can start from there. What is the propellant mass required for the second stage of Agni 2 if the payload + inert weight is dropped by the weight of the third stage of Agni V. We can ignore the higher Isp and more efficient stage separation for now.

I presume this is a new discussion topic. Or could you clarify it by elaborating it?